Yes the game sounds great with Roland (Munt emulator).
So how far did you get with that video? Do you have the Munt emulator already installed, and have obtained the Roland MT-32 and/or CM-32L PCM and control ROMs?
The video seemed quite good in explaining what one needs to do, the main thing might be how to tell the game itself (Red Baron) to use Roland MIDI for music and sound effects. That last step depends on the game, as different DOS games have different ways to setup the audio part (quite often running something like setup.exe, install.exe, setsound.exe or similar within DOSBox; some games autodetect it or let you choose it from within the game), and unfortunately with some games GOG has removed the sound setup program in which case you need to edit some game config file directly.
I can look into it more when I get home. Or, let me know if you already figured it out by yourself.
I've got as far as step 4, with the Munt emulator up and running, but in this vid there's a convenient settings program that does the final tweak to enable the emulator, which Red Baron just doesn't have. The video guy mentions he shows the manual way to do it in his Wing commander 2 video, which I checked out here: https://www.youtube.com/watch?v=UwWeN_2DL8k
but in that one, he goes into dosbox and types dir to open the directory, and when you do that for Red Baron, it doesn't notice the same install files in the folder even though they are there, so I've hit a roadblock at the very last step. It's driving me crazy getting so close with no luck!